Concurrent T cell leukaemia and equine multinodular pulmonary fibrosis in a Hanoverian Warmblood mare

Abstract

Equine multinodular pulmonary fibrosis (EMPF) and primary leukaemia are uncommon diseases in horses. This case report describes a horse with both diseases which might be linked via the equine g-herpesvirus EHV-5. In man Epstein Barr Virus (EBV), also a g-herpesvirus, is associated with idiopathic pulmonary fibrosis as is EHV-5 with EMPF. Furthermore, EBV is also associated with lymphoproliferative disease. Similarly in horses, primary leukaemia might be associated with EHV-5. This is the first report associating EHV-5 with primary leukaemia in horses.

Systemic Granulomatous Disease in a Hungarian Warmblood Gelding

“…The gammaherpes viral genes are capable of modulating cellular signals such that cell proliferation and viral replication occur at the appropriate times in the viral life cycle [22]. Regular EHV-5 infection has been demonstrated in EMPF cases to induce a milieu of Th2 cytokines resulting in extensive fibrosis, similar to the pathology caused by EBV in human idiopathic pulmonary fibrosis [23]. Interestingly, SGD is a Th1-mediated disease, but EHV-2, another gammaherpesvirus, was proved to induce this type of exaggerated immune response in a dermatologic case [13].…”

“…Further, another gammaherpesvirus, asinine herpesvirus 5 (AHV-5), caused pyogranulomatous pneumonia in a mare [24]. Multinucleated giant cells and macrophages are also characteristic findings in EMPF histopathology [3,23]. In human pulmonary sarcoidosis, pathologic changes can range from predominantly granulomatous inflammation with minimal chronic changes through to extensive fibrosis with few granulomas.…”

“…Increased numbers of polymorphonuclear cells are found in the BAL fluid of human patients with sarcoidosis when there is radiological evidence of established fibrosis, and the degree of neutrophil alveolitis correlates with severity [8]. Neutrophilia and hemosiderophagia in the pulmonary fluid are typical findings in EMPF with fibrosis and lung tissue destruction [23]. There is no previous description of BAL cytology in equine SGD.…”

Advanced multicentric lymphoma in a Belgian Draft Horse mare

“…Equine lymphoma arises from lymphoid tissue and is conventionally categorized according to the distribution of tumour lesions as alimentary, cutaneous, mediastinal or multicentric (Schwarz et al 2012, Ness 2016, Taintor and Schleis 2011.…”

“…Leukaemia can be classified by the cell of origin as myeloproliferative or lymphoproliferative, and by maturation stage as acute (blast cells in the circulation) or chronic (mature differentiated cells in the circulation). The presence of neoplastic cells in the circulation can be further differentiated into leukaemic, subleukaemic and aleukaemic forms (Muñoz et al 2009, Schwarz et al 2012.…”